Method and flame generating apparatus for flame photometry



Jan. 9, 1962 J. J. J. STAUNTON 3,015,933

METHOD AND FLAME GENERATING APPARATUS FOR FLAME PHOTOMETRY Filed Sept. 29, 1954 4 Sheets-Sheet 1 Jan. 9, 1962 J. J. J. STAUNTON ,0 8

METHOD AND FLAME GENERATING APPARATUS FOR FLAME PHOTOMETRY Filed Sept. 29, 195 4 Sheets-Sheet 2 & IgVENTOR.

3,015,983 METHOD AND FLAME GENERATING APPARATUS FOR FLAME PHOTOMETRY Filed Sept. 29, 1954 Jan. 9, 1962 J. J. J. STAUNTON 4 Sheets-Sheet 3 INVENTOR. M 3. )1. diam/n M CAN/V19 Mozsfiflc/v Jan. 9, 1962 J. J. J. STAUNTON 3,015,933

METHOD AND FLAME GENERATING APPARATUS FOR FLAME PHOTOMETRY 4 Sheets-Sheet 4 Filed Sept. 29, 1954 United States Patent Ofilice 3,615,983 Patented Jan. 9, 1962 3,015,983 METHOD AND FLAME GENERATING APPA- RATUS FOR FLAME PHOTOMETRY John J. J. Staunton, Oak Park, 111., assignor to Coleman Instruments, ind, Maywood, 111., a corporation of Illinois Filed Sept. 29, 1954, Ser. No. 459,084 22 Claims. (Cl. 88-44) This invention relates to novel and useful improvements in methods and apparatus for analysis by flame photometry.

In the analysis of a solution by flame photometry, it is essential that the material be introduced into the flame in a finely divided form and the temperature of the flame used should be as high as practical so that materials which are not readily excited can be caused to give out radia- 'tions which can be analyzed. Moreover, the flame should be concentrated and should not change its size or shape or wander so as to enable the flame to be optically directed into a photometric system in an eflieient manner.

In order to provide the desired intense flame, it is neccessary to feed an adequate quantity of combustible gas to the flame with a sufficient quantity of combustion supporting gas to effect substantially complete combustion of the combustible gas. In previous burners, the combustible gas mixture has been fed from the burner with an appreciable forward velocity that is, a velocity in a direction from the base to the tip of the flame. As the gas issues from the burner ports with a forward velocity, this velocity will decrease as soon as the gas starts to expand upon leaving the burner ports and the flame front will be established at the point in the stream where the gas velo city has dropped to the velocity of flame propagation of the gas mixture. If the velocity of the gas mixture as it leaves the burner ports exceeds the rate of flame propagation of the mixture, then the flame front is established at a point spaced from the burner ports at which the velocity of the gas stream is reduced to the rate of flame propagation. However, the rate of change of velocity of the gas mixture decreases rapidly as the distance from the burner increases and therefore if the mixture is such that the velocity of the stream is reduced to the velocity of flame propagation of the gas mixture only after the stream has passed a relatively large distance from the burner, then any minor changes in the mixture of combustible gas to combustion supporting gas or any small changes in the velocity of the stream as it issues from the burner will cause major changes in the point at which the flame front is established and produce an unstable flame which will eventually blow out. It is therefore necessary in this type of burner to premix a large quantity of combustion supporting gas with the combustible gas to increase the rate of flame propagation of the mixture so that it burns close to the burner to produce a stable flame. If the velocity of the mixture as it issues from the ports is less than the velocity of'flame propagation of the mixture, then the flame front is established at the burner ports and will cause the burner to be heated excessively by the base of the flame. In this type of operation it is necessary to provide some means for cooling the burners to prevent the latter from reaching an excessively high temperature.

An important object of this invention is the provision of a burner for a flame photometer which will produce a high flame temperature for exciting the samples to their characteristic radiation spectra using gases having low rates of flame propagation.

Another object of this invention is the provision of a burner for a flame photometer which will provide a stable and concentrated flame which may be eficiently optically focused into the photometric system.

Another object of this invention is the provision of a burner for a flame photometer which can be readily assembled and disassembled for cleaning.

Still another object of this invention is the provision of a burner having an atomizer for ejecting a mist of the sample into the flame, which atomizer can be readily and easily cleaned without interrupting the operation of the burner.

Yet another object of this invention is to provide an apparatus for analysis by flame photometry in which the burner is arranged in the instrument casing so as to draw air over the electrical apparatus in the casing and effect cooling of the apparatus, and in which the casing is so arranged as to muflle the burner noise.

A further object of this invention is the provision of an apparatus for analysis by flame photometry including a burner casing having a door arranged to support the sample container and move the latter into and out of position below the atomizer intake tube as the door is respectively closed and opened, and which is arranged to elevate and lower the sample container in response to movement of the door latch to its latched and unlatched position respectively, whereby the door cannot be opened and the sample container removed from the housing until after the sample container has been lowered, thereby preventing accidental damage to the atomizer intake tube.

These, together with various ancillary objects and advantages will be more readily appreciated as the same becomes better understood by reference to the following detailed description when taken in connection with the accompanying drawings wherein:

FIGURE 1 is a top plan view of the apparatus for use in analysis by flame photometry;

FIG. 2 is a fragmentary top plan view of the apparatus showing the burner mounted in the burner chimney;

FIG. 3 is a fragmentary vertical sectional view through the burner chimney;

FIG. 4 is a fragmentary top plan view of the sample container support and elevating mechanism, parts being broken away and shown in section to illustrate details of construction;

FIG. 5 is a fragmentary vertical sectional view taken on the plane 55 of FIG. 4;

FIG. 6 is an enlarged vertical sectional view through the atomizer orifice showing the matmer of positioning the sample intake tube therein;

FIG. 7 is a fragmentary sectional view taken on the plane 77 of FIG. 6;

FIG. 8 is a fragmentary horizontal sectional view taken on the plane 8-8 of FIG. 6;

FIG. 9 is an enlarged vertical sectional view through the burner;

FIG. 10 is an enlarged vertical sectional view through the atomizer, and

FIG. 11 is a longitudinal sectional view of a cleaning tool for the atomizer.

Reference is now made more specifically to the accompany drawings. The flame photometer, as shown in FIGURE 1, includes a casing having a bottom wall 15, a top wall 16 and upstanding side walls 17 and end walls 18 extending between the top and bottom. A cylindrical chimney 19 (see FIG. 2) is located at one corner of the casing and separates the casing into a burner compartment 21 and an instrument compartment 22. A chimney extension 23 is mounted on top of the chimney 19 and extends upwardly therefrom. As best shown in FIG. 3, the chimney 19 has an upstanding peripheral flange 24 which is received in the corresponding peripheral recesses 25 in the chimney extension whereby the latter is removably supported on the chimney. Both the chimney and, the chimney extension are lined with a layer of a heatresistant acoustical insulating material 26 to reduce the burner noise and prevent the chimney and the chimney extension from becoming heated by the burner flame.

One side of the chimney 19 is provided with an opening 27-therein (see FIG. 2) for the reception of suitable filters, and a beveled slot 29 is formed on the chimney 19 in communication with the opening 27 to enable insertion and removal of the filters from outside of the casing. A lens 32 is supported by the bracket 33 in the notches 34 in the chimney wall and is arranged to optically focus the burner flame throgh the filters disposed in the opening 27 onto a photocell which forms a part of the photometric apparatus 28 disposed in the instru ment compartment 22 of the casing. As is well known, the output of the photocell varies as a function of the light intensity impinging thereon, and is measured by the photometric circuit which actuates a suitable indicator.

The burner 31 when in operation produces a draft in the chimney and an opening is provided in the lower end thereof to permit the circulation of air through the chimney. In accordance with the present invention, the opening 35 is located in the bottom of the chimney in the portion thereof which extends between the burner compartment 21 and the instrument compartment 22 so that the air is drawn from the instrument compartment and flows upwardly through the chimney. Consequently, the air which enters the chimney is baffled by the casing and no external cross-drafts can enter the lower part of the chimney. Moreover, the drawing of air through the instrument compartment effects cooling of the several electrical compartments disposed therein, and in addition communication between the burner compartment and the instrument compartment elfects a muffling of the burner noise. Suitable openings are provided in the casing to admit air thereinto, and are arranged so that the air which enters these openings passes through the instrument compartment over the photometric apparatus 28 to the opening in the chimney.

The burner 31 is of the direct-injector type wherein the sample being analyzed is directly injected into the base of the flame and is ionized thereby to produce the characteristic radiation spectra of the elements contained in the liquid. In order to produce a high temperature flame which is stable and concentrated so that it may be efficiently optical-1y focused by the lens onto the photometric apparatus and in which the flame burns at a point spaced from the burner so as to not excessively heat the latter, the burner is constructed to feed the combustible gas in such a manner as to produce a mass of the gas mixture which has a negligible forward velocity, that is, a negligible velocity in the direction from the base to the tip of the flame. A combustion supporting gas such as oxygen, is then directed through the mass of combustible gas at a velocity greater than the maximum rate of flame propagation through the gas to entrain a certain amount of the combustible gas therein and become turbulently intermixed with the combustible gas along the path of the combustion supporting gas stream. In this manner, a combined gas stream of combustible gas and combustion supporting gas is fed to the base of the flame.

The location of the flame front relative to the injector for feeding the combustion supporting gas stream is determined by the velocity of the combined gas stream and by the mixture of combustible gas and combustion supporting gas therein, the flame front being established when the velocity of the combined gas stream is reduced, due to turbulence and expansion, to the velocity of flame propagation of the mixture. However, the rate of change of velocity of the combined stream decreases as the distance from the burner increases and the burner of the present invention is arranged to establish the flame front at a point sufficiently near the burner so that the rate of change of velocity of the stream is high. Under these conditions, minor changes in mixture of combustible gas to combustion supporting gas, which change the rate of flame propagation, and minor changes in the velocity of the combustible gas stream and the combustion supporting gas stream which make up the combined stream, do not materially change the position of the base of the flame. Thus, if the mixture should vary and change the rate of flame propagation, the position of the base of the flame would shift but slightly to a position at which the velocity of the combined gas stream again equals the velocity of flame propagation. Since, as previously described, the base of the flame is established in a region sufliciently near the burner so that the rate of change of velocity of the combined gas stream is high, only small variations in the position of the base of the flame will be produced by fluctuations in the rate of flame propagation or velocity of the constituent gas stream.

In order to effect burning of the combined stream at a point spaced from the burner to eflect cool operation thereof and yet sufficiently close to the burner so as to produce a high rate of change of velocity of the combined stream, a combustion supporting gas is premixed with the combustible gas to produce a mixture at or below the lower limits of inflammability. Since the mixture issuing from the burner is below the limits of inflammability, the gas does not burn in contact with the burner which would cause excessive heating thereof. However, by premixing a combustion supporting gas with the combustible gas, the mixture when entrained in the combustion supporting gas'stream produces a combined stream which is above the lower limits of inflammability in the region near the burner at which the rate of change of velocity of the combined stream, due to turbulence and expansion, is high. If a small quantity of combustion supporting gas were not premixed with the combustible gas, then the combustion supporting gas stream and the combustible gas stream would combine to produce a combined gas stream having a low rate of flame propagation and then only at a relatively great distance from the burner. This is in the region in which the rate of change of velocity of the combined gas stream is low, and consequently minor changes in the mixture or velocity of the constituent streams would produce marked changes in the position of the flame and even cause the flame to blow out.

The rapid rate of change of velocity of the combined gas stream in a region near the burner is eifected by reducing the velocity of the combustible gas stream to as low as possible so that the combustion supporting gas stream passing therethrough produces turbulent intermixing which is not achieved by laminar flow of the combustible gas stream and the combustion supporting gas stream as occurs when the combustible gas stream has an appreciable forward velocity. The turbulence produced by passing the combustion supporting gas at a high velocity through a relatively stationary mass of combustible gas not only effects a rapid reduction in the velocity of the combined stream but also produces turbulent intermixing which renders the flame more steady and effects a flame having a higher temperature. Thus, the flame produced by the burner of the present invention is concentrated since only the combustible gas. which becomes intermixed with the stream of combustion supporting gas is caused to burn. Since the injec-' tion of the combustion supporting gas into the combustible gas mixture in this manner produces thorough intermixing of the gases and also rapidly reduces the velocity of the combined gas stream due to the turbulent intermixing, the flame front does not vary with slight variations in the combustible gas mixture which is fed to the flame or with small fluctuations in the velocity at which the combustion supporting gas is discharged from the atomizer. Moreover, since the flame burns at a distance from the burner, the latter is not heated thereby and consequently may be operated at a low temperature even after prolonged periods of operation.

The burner, as best shown in FIG. 9, comprises a burner body 41 having an upstanding cylindrical outer wall 42 and a tubular inner wall 43 secured thereto or formed integrally with the closed bottom 44. A conduit 45 is secured to the burner body and communicates with the Space between the inner and outer walls thereof, the conduit extending through an opening 46 in the chimney 19 to support the burner within the chimney concentrically thereto. The outer wall 42 of the burner body has an inner peripheral recess 47 formed therein adjacent the upper edge thereof and an annular baffle plate 48 is adapted to rest on the shoulder formed by the recess. The baflle plate extends between the outer wall and the inner wall and is slidably supported on the latter so that the bathe may be readily assembled and disassembled from the burner body. A depending sleeve 49 is preferably formed integrally with the baflie plate 48 and a radially extending baffle member 51 eXtendS outwardly of the lower end thereof, the periphery of the bafiie member 51 being spaced from the inner surface of the outer wall 42 to form a flow restricting passage which limits the rate of flow of the gas mixture thereby so that the gas mixture is distributed uniformly around the burner body. The bafiie 51 is spaced from the baffle plate 48 and forms a chamber therebetween which permits the gas mixture flowing past the baflie 51 to expand, thereby improving the mixing of the gas and producing turbulence which reduces the forward velocity thereof. A plurality of annularly spaced openings 52 are formed in the baffle plate 48 and limits the rate of flow of the combustible gas outwardly from between the inner and outer walls of the burner body to improve the distribution of the gas mixture around the burner body, and an annular difluser or spreader plate 53 is disposed on the tubular inner wall 43 and overlies the openings 52 in the bafi'le plate to deflect the combustible gas issuing therefrom outwardly over the beveled upper edge 54 of the outer wall 42 and further reduce the velocity of the gas issuing from the burner body. For reasons set forth more fully hereinafter, the dilfuser plate 53 is preferably formed of a material having low heat conductivity, such as the plastic sold under the trade name Teflon, and the latter is provided with a depending annular flan e 55 which engages the upper face of the baffle plate 48 and supports the diffuser plate in vertical spaced relation thereto.

A housing is disposed around the burner body and extends upwardly therefrom to form an enlarged chamber above the diffuser plate 53 for the reception of the combustible gas. In accordance with the present invention, the housing is formed by an upper annular ring 53 having an annular recess 59 formed in the inner lower edge thereof which receives a corresponding annular flange 61 on the upper edge of a ring member 62. The latter is disposed about the outer wall of the burner body and is preferably formed of a material having low heat conductivity such as the plastic Teflon previously mentioned. The lower ring 62 supports the upper ring in proper position with respect to the burner body and thermally insulates the upper ring from the burner body so that the latter does not become heated by conduction from the ring 58. The upper edge of the ring 58 is charnfered as indicated at 63 to support a frusto-conical screen 64, the lower open end 64a of which is disposed concentrically of the burner body and spaced above the upper end thereof. Conveniently, the upper edge of the ring 58 may be rolled inwardly as indicated at 65 to clamp the screen 64 to the ring member.

The gas mixture, as it enters through the conduit 45, thus passes upwardly between the inner and outer walls of the burner body into the chamber below the baflie member 51 which elfects mixing of the combustible gas and the combustion supporting gas and also distributes the gas mixture uniformly around the burner body, the mixture passing upwardly through the passage formed between the baflie 51 and the outer wall of the burner body and expanding into the chamber above the bafile U 51 thereby further reducing the forward velocity of the mixture. The mixture then passes through the passages 52 which limit the rate of flow of the gas mixture from the burner body. As the gas mixture passes through the passages 52, it is deflected outwardly by the diffuser plate 53 which further reduces the velocity of the gas in an upward direction so that the gas entering the chamber defined by the ring 58 has negligible forward velocity. The velocity of the gas is further reduced as it passes through the screen 64, the latter being of inverted frustoconical configuration to more evenly distribute the combustible gas mixture along the stream of combustion supporting gas from the atomizer.

The atomizer comprises a tubular body 71 (see FIGS. 9 and 10) having an annular recess 72 formed in the upper end thereof for the reception of a plate 73, the upper edge of the body 71 being spun over onto the plate to fixedly secure the latter to the tubular body. The tubular body is snugly received within the inner wall 43 of the burner body 41 and has a conduit 74 connected thereto adjacent the lower end for passing a combustion supporting gas such as oxygen into the atomizer body. The plate 73 has an orifice 75 (see FIGS. 6, 7 and 8) formed centrally thereof, the upper edge of which is beveled as at '76, as is clearly shown in FIG. 6 of the drawings. A liquid intake tube 77 extends concentrically through the atomizer body 71 and is formed with an outer diameter equal to the inner diameter of the opening '75 in the cover plate. A plurality of flats 78, here shown three in number, are ground on the periphery of the intake tube 77 at a point spaced from the upper discharge end thereof to permit the passage of the combustion supporting gas through the opening 75 when the tube is positioned therein. The upper end portion 79 of the tube is ground to a circular cross-section, as shown in FIG. 7, for a distance from the upper end thereof less than the thickness of the plate 73, which annular discharge end 79 extends upwardly through the opening 75. As is apparent, the outer periphery of the intake tube is received in the opening 75 and serves to properly locate the capillary tube concentrically to the opening 75 and the flats 78 form a plurality of annularly spaced flow passages for the combustion supporting gas. The radius of the cylindrical end portion 79 is made larger than the radial spacing of the flats 78 so that the crosssectional area of the annular flow passage formed between the cylindrical end portion 79 and the opening 75 in the plate is less than the cross-sectional area of the annularly spaced flow passages formed by the flats 78. The relatively constricted passage formed between the cylindrical end portion 79 and plate 73 limits the rate of flow of the combustion supporting gas so that the separate gas streams which flow by the flats 78 are uniformly distributed around the periphery of the annular end portion of the nozzle and form a continuous sheath of combustion supporting gas as it emerges from the opening 75, around the end of the intake tube. Preferably the surface of the cylindrical end 79 is roughened slightly to produce turbulence and assure uniform distribution of the gas around the upper end of the tube and the upper end 80 of the intake tube is ground flat to provide sharp outer edges. The sample as it flows up through the intake tube clings to the surface thereof and flows radially outwardly on the upper end 80 to the outer edge where it passes into the upwardly flowing sheath of gases in minute droplets.

In accordance with the present invention the capillary tube 77 is mounted within the atomizer body 71 so as to be movable relative to the plate 73 to permit cleanin of the orifice opening 75. For this purpose a plug 81 is affixed to the capillary tube intermediate the ends thereof and is provided with a beveled underside 82 which is adapted to seat on the inwardly extending beveled shoulder 83 formed by flaring the lower end of the atomizer body 71 inwardly. A compression spring is disposed within the atomizer body between the plate 73 and the plug 82 to normally urge the plug into engagement with the shoulder 83 to seal the lower end of the atomizer body. In order to clean the hole in the opening 75 it is only necessary to urge the plug 81 upwardly which moves the upper end of the capillary tube upwardly through the orifice 75 thereby cleaning the tion of the capillary 77 into engagement with the plug 1 81 to move the capillary tube upwardly and clean the opening 75 in the nozzle plate. In order to clean the inside of the capillary, the wire 85 is inserted upwardly in the tube from the lower end thereof, the length of the wire being chosen so that it does not project at the top of the capillary tube sufficiently to enter the hot part of the flame when the tool body contacts the plug 81. In this manner, the bore in the capillary tube as well as the orifice opening 75 can be cleaned while the burner is in operation. 7

The stream of combustion supporting gases such as oxygen issuing from the orifice opening 75 around the capillary tube flows through the mass of gas in the chamber defined by the annular ring 58 and draws gas from this chamber and mixes with the latter to produce a combined gas stream of the combustible gas and the combustion supporting gas. The combustion supporting gas is preferably flowing in a stream at a velocity greater than the maximum velocity of flame propagation through the gas, and the combustible gas is in a mass having a negligible forward velocity whereby the combustion supporting gas effects turbulent intermixing with the combustible gas. The flame produced by this combined gas stream will have a flame front located a distance from the atomizer orifice at which the velocity of the combined gas stream diminishes, due to turbulent intermixing with the combustible gas and due to expansion after leaving the atomizer, to the velocity of the flame propagation through the combined gas stream. The stream of combustion supporting gas issuing from the opening 75 around the liquid intake tube 77 produces a Venturi effect and draws liquid upwardly through the tube and atomizes the same when the latter reaches the top, the atomized liquid being carried directly into the base of the flame where it is ionized and the constituent elements excited to give off their characteristic radiation spectra.

Since the combustion occurs in the path of the combustion supporting gas stream, where the intermixing with the combustible gas is effected, it is apparent that the atomized liquid sample is introduced directly into the flame so that complete ionization of the liquid is effected.

In order to reduce the effects of cross drafts within the chimney 17 and the chimney extension 23, an upstanding cylindrical screen 88 is provided, the lower end of the screen being disposed about the annular ring 58 and supported by the outwardly extending shoulder 89 formed thereon, the screen extending upwardly from the ring 5-8 a distance approximating one-halfthe normal flame height which is somewhat greater than the height of the observed part of the flame.

Provision is also made for positioning the sample container 91 below the lower end of the liquid intake tube 77 so that the latter may draw liquid therefrom. An arcuate door 101 is hingedly connected to the chimney 19 and forms a continuation of the side walls thereof so that when the door is closed the chimney defines a closed compartment having an open upper end and an air inlet opening 35 adjacent the bottom. An upstanding rib 102 is preferably formed along the edge of the door opening and forms a stop for the door, the rib having a keeper 103 formed integrally therewith. A latch knob 104 having a shaft 1%5 is provided on the door, the shaft extending through a bushing 106 in the door, as is clearly shown in H6. 4. An L-shaped bracket formed of fiat sheet stock has one leg 107 thereof mounted on the bushing and fixedly secured thereto, the other leg 108 of the bracket extending forwardly of the bushing and having a laterally extending ear 109 formed on the outer end thereof. An ear 111 is formed on the free end of the legllki and projects forwardly therefrom, and a bail 112 having inwardly extending fingers 113 is vertically pivotally supported on the bracket and carries at its forward end an annular cupshaped member 114 for receiving and supporting the samle container 91. A crank 115 having a shaft 116 disposed in axial alignment with the shaft is journaled at one end in the ear 109 and has an offset portion 117 which extends through the shaft 105 and is rigidly secured thereto whereby the crank shaft 116 is rotated about the axis of the shaft 105 as the latter is rotated by the knob 104. Consequently, rotation of the knob effects movement of the crank to elevate and lower the cup-shaped member 114 as the knob is rotated. The latch arm 118 is formed integrally with the offset portion 117 and extends outwardly from the shaft 105, an arcuate latch finger 119 being formed on the outer end of the latch arm 118. The latching finger is formed concentric with the shaft 105 and the arm 113 is angulated with respect to the crank in such a manner that the arcuate latching finger engages the keeper 103 formed on the chimney 19 at all times except when the shaft 105 is rotated to a position so that the crank 115 is in its lowermost position. By this arrangement the knob 104 not only controls elevating and lowering of the sample container 91 but in addition controls latching of the door in such a manner that the door cannot be opened or closed until the container 91 is moved to its lowermost position. Consequently, damage to the capillary tube 77 due to moving the sample container or beaker 91 into and out of the housing is prevented.

In operation, a combustible gas is supplied through conduit 125, through mixer 126 to the conduit 45 which supplies gas to the burner body. Combustion supporting gas, such as oxygen, is supplied through conduit 127 and throttle valve 128 to the mixer'126 so that the gas supplied to the burner body contains a combustible gas and a combustion supporting gas in a preselected mixture. In accordance with the present invention, the amount of combustion supporting gas such as oxygen fed to the mixture 126 is such that the resultant mixture of combustible gas and combustion supporting gas is below the lower limits of flammability of the gas so that the mixture itself will not support combustion. This mixture passes around the baflle 51 where the combustible gas and the combustion supporting gas are intermixed and distributed around the burner body and passes outwardly of the burner body through the flow restricting passages 52 which limit the rate of flow of gas so that the gas passing into the chamber defined by the ring 58 has a negligible component of forward velocity. The baffle plate 53 which overlies the passages 52 directs the combustible gas outwardly as it flows into the chamber within the ring 58 to reduce the forward velocity of the gas and the gas then passes through the reticulated screen 64 which further reduces the velocity of the mixture in the forward direction, that is, in the direction from the base to the tip of the flame. The combustion supportng gas supplied through conduit 74 produces a high speed jet or stream as it passes through the atomizer orifice 75 which stream is preferably at a velocity higher than the maximum velocity of flame propagation for the gas. The jet of combustion supporting gas, as it passes through the mass of combustible gas, entrains some of the combustible gas therewith. Since the combustible gas mixture has negligible forward velocity, and the combustion supporting gas has a high forward velocity, turbulent intermixing is effected and the velocity combined stream of combustion supporting gas and combustible gas is rapidly reduced to a velocity equal to the velocity of flame propagation for the combined gas stream at a distance from the atomizer orifice. As the mixture fed from the burner is slightly below the lower limits of inflammability, only a small quantity of combustion supporting gas need be added thereto to provide a flame supporting mixture and this occurs at a point spaced from the burner body but sufliciently close thereto to be in the region where the rate of change of velocity of the combined stream is high. It is at this point that the flame front is established, which flame front is relatively stable since it is substantially independent of the mixture of combustion supporting gas and combustible gas fed through the conduit 45 and is also substantially independent of the velocity of the combustion supporting gas issuing from the atomizer orifice. Moreover, since adequate combustion supporting gas is present only in the path of the jet from the orifice, the flame produced will be concentrated and will have a high flame intensity since adequate combustion supporting gas is provided in this confined zone. The flame thus burns at a point spaced from the burner and does not tend to heat the same. Moreover, the mass of combustible gas lies between the flame and the burner so as to insulate the burner against radiation from the flame, the incoming combustible gas being preheated by radiation from the flame thereby increasing the intensity of the flame produced by the combined gas stream.

Some burning of the combustible gas mixture occurs at the front between the combustible gas mixture in the chamber defined by the ring 58 and the air in the chimney, and this causes some heating of the screen 64 and the supporting ring 58. However, since this ring is thermally insulated from the burner, the heat is not conducted to the burner. Moreover, the temperature of the screen and ring 58 is not excessive and serves the useful purpose of preheating the combustible gas mixture as it passes therethrough. The screen 88 is provided to reduce the cross drafts in the chimney and thereby improve the stability of the flame.

The flame from the burner in the chimney produces an upward draft therein which draws air through the opening 35 in the bottom of the chimney from the instrument compartment 22 in the housing. The drawing of air from the instniment compartment serves to aid in cooling the components of the photometric apparatus contained therein and in addition this arrangement for drawing air from the instrument compartment reduces turbulence within the chimney since it effectively baffles the incoming air against the cross drafts. Moreover, the opening in the bottom of the chimney which communicates the burner compartment with the instrument compartment adap s the latter to function as a mufller to reduce the burner noise without in any manner impeding the uniform flow of air upward in the chimney. Thus cross drafts and turbulence in the chimney are substantially eliminated.

When inserting and removing a sample it is only necessary to position the sample container 91 on the support ring 114 and then close the door and turn the knob 164. The latter both elevates the sample container 91 and moves the latch finger 119 into its latching position against the keeper 121. Similarly, when removing the sample from the chimney, it is necessary to first turn the knob 104 to lower the container and release the latch finger from engagement with the keeper arm, after which the door latch opens to withdraw the sample container from the chimney.

Cleaning of the atomizer orifice 75 and the capillary tube 77 can be effected while the burner is in operation by using the tool shown in FIG. 11, which tool has a wire which is receivable in the bore in the capillary tube to clean the inside of the capillary. The length of the wire 85 which extends beyond the body 86 is only slightly greater than the length of the capillary tube so that when the wire is completely inserted in the capillary, the body engages the lower end of the capillary and prevents the tip of the wire from extending into the hot part of the flame. The outer tubular body is adapted to be inserted over the lower end portion of the capillary tube into engagement with the plug whereby the latter may be elevated to move the capillary tube upwardly in the orifice plate 73 to clean the same.

I claim:

1. In a flame photometer, a burner for producing a flame, an atomizer including an intake tube for feeding a sample to the flame, a casing surrounding the burner having an access door therein, means on said door for supporting a sample container for movement with the door to a position below the intake tube as the door is moved to its closed position, and means on said door for elevating the sample container into operative position where the intake tube dips into the sample in the container.

2. In a flame photometer, a burner for producing a flame, an atomizer including an intake tube for feeding a sample to the flame, a casing surrounding the burner having an access door therein, means on said door for supporting a sample container for movement with the door into and out of position below the intake tube, latch means operable to latch said door in its closed position, and means responsive to movement of the latch means into and out of latching position for respectively elevating the sample container into operative position Where the intake tube dips into the sample in the container and for lowering the sample container below the end of the intake tube.

3. In a flame photometer, a burner for producing a flame, an atomizer including an intake tube for feeding a sample to the flame, a casing surrounding the burner having an access door therein, means on said door for supporting the sample container for movement with the door into and out of position below the intake tube, said container support means including means for supporting the container on the door for vertical movement relative thereto, latch means on said door operable to latch said door in its closed position, and means responsive to movement of the latch means into and out of latching position for respectively elevating and lowering the sample container.

4. In a flame photometer, a burner for producing a flame, an atomizer including an intake tube for feeding a sample to the flame, a casing surrounding the burner having an access door therein, means on said door for sup porting the sample container for movement with the door into and out of position below the intake tube, said container support means including means for supporting the container on the door for vertical movement relative thereto, latch means including a shaft rotatably journaled in said door, crank means operatively connected to said shaft and responsive to rotation thereof for elevating and lowering said container, and latch means operatively connected to said shaft for locking the door in its closed position in response to rotation of the shaft in one direction and for unlocking the door in response to rotation of the shaft in the other direction.

5. The combination of claim 4 wherein said latch means includes a latch finger shaped to retain the door in its locked position Whenever the crank means is in a position other than the position thereof in which the container is lowered below the end of the intake tube.

6. In a flame photometer, a casing having a bottom Wall, side and end walls and a top wall, a partition in said casing separating the latter into an enclosed instrument compartment and a burner compartment having an open top, a burner in said burner compartment for producing a flame, an atomizer including an intake tube for feeding a sample to be analyzed to the flame, said casing having an access door opening into said burner compartment, means on said door for supporting a sample container for movement with the door to a position below the intake tube as the door is moved to its closed position, and means for elevating the sample container into operative position where the intake tube extends into the sample in the container, said partition means having an opening therein adjacent the lower end of said burner compartment communicating the latter with the instrument compartment, said casing having air inlet openings communicating said instrument compartment with the atmosphere for admitting air into said instrument compartment to be drawn therethrough and through said first mentioned opening into the burner compartment by the draft produced by said burner.

7. In a flame photometer, a burner for producing an analytical flame comprising an upright burner body having a connection for receiving a supply of combustible gas,

' an injector disposed concentrically of said body and hav ing a connection for receiving a combustion supporting gas, said injector having an orifice in the upper end thereof for discharging a jet of combustion supporting gas, a housing surrounding said burner body and extending upwardly from the upper end of the injector and having an unrestricted open top, said burner body having passages therein located below the upper end of said injector for producing an upwardly flowing annular stream of combustible gas surrounding said injector, baflle means overlying said passages and disposed in the path of said combustible gas stream for reducing the velocity thereof sufflcient to produce a substantially quiescent mass of gas having a negligible velocity in the direction of flow of said jet of combustion supporting gas, and a frustoconical screen disposed above said bafiie means and having the minor end disposed adjacent the upper end of the injector concentrically to said orifice and the major end attached to said housing above said upper end of the injector for distributing the combustible gas along the jet of combustion supporting gas to be carried thereby to the flame.

8. In a flame photometer, a burner for producing an analytical flame comprising a burner body having a bottom and concentric inner and outer walls extending upwardly from the bottom, a baffle plate slidably received on the inner wall and extending outwardly therefrom into engagement with the outer wall to be supported thereby in spaced relation to the bottom of the body, conduit means communicating with said burner body between said inner and outer walls for supplying a combustible gas thereto, said baffle plate having passages therein for passing the combustible gas from the burner body, means defining a chamber above the baffle for receiving the combustible gas from the body, a diffuser plate slidably received on said inner wall of the body and extending outwardly therefrom in overlying relation to said passages in the baffle plate to deflect the combustible gas issuing from the passages outwardly and to reduce the velocity of the combustible gas in a direction axially of the burner body, and means extending through said inner wall for directing a stream of combustion supporting gas through said chamber to draw combustible gas therefrom and feed the combustible gas to a flame.

9. In a flame photometer, a burner for producing an analytical flame comprising a burner body having a bottom and concentric inner and outer walls, said outer wall having an inwardly facing recess adjacent the upper end thereof, a baffle plate slidably disposed on said inner wall and extending outwardly therefrom into said recess to be supported by the outer wall, conduit means communicating with said burner body between said inner and outer walls for supplying a combustible gas thereto, said baffle plate having a plurality of flow restricting passages therein for passing the combustible gas from the burner body,, a sleeve carried by said baffle plate and extending downwardly therefrom, an outwardly extending flange on the lower end of said sleeve terminating in spaced relation to said outer wall, a diffuser plate slidably received on said inner wall and having 21 depending flange thereon engaging said baflle plate to support the diffuser plate thereabove, said diffuser plate overlying said passages to deflect the gas issuing therefrom outwardly to thereby reduce the forward velocityof the gas, means defining a chamber above said diffuser plate for receiving the combustible gas from the burner body, and means extending through said inner walls for directing a stream of combustion supporting gas through the chamber to draw combustible gas therefrom and feed the combustible gas to a flame.

10. In an apparatus for flame photometry, a burner comprising a burner body having a connection for receiving a combustible gas, an atomizer body extending concentrically through said burner body and having a connection for receiving a combustion supporting gas, said atomizer body including a top wall having a discharge orifice in the upper end thereof for passing a stream of combustion supporting gas at a high velocity, a housing surrounding said burner body and extending above the discharge orifice in said atomizer body to form a gas receiving chamber thereabove, said burner body having a plurality of passages therein located below said top wall of said atomizer body for passing a hollow stream of combustible gas into said chamber suflicient to produce a substantially quiescent mass of gas having a negligible velocity in the direction toward the open end of the chamber, baffle means overlying said passages to reduce the velocity of the combustible gas flowing into said chamber, and a liquid intake tube extending through said atomizer body and having the discharge end thereof disposed concentrically to said orifice and spaced from the walls thereof to permit the flow of combustion supporting gas through said orifice alongside said intake tube to draw liquid therefrom for passage with the stream of combustion supporting gas to the flame.

11. The combination of claim 10 wherein said intake tube has an external diameter equal to the diameter of said orifice, a plurality of flow passages formed in the periphery of said tube and spaced from the discharge end thereof a distance less than the thickness of said top wall to permit the flow of combustion supporting gas therethrough and a reduced diameter cylindrical end on said intake tube extending from the discharge end a distance,

less than the thickness of said top wall.

12. The combination of claim 10 including a plug se cured to said tube intermediate the ends thereof, an inwardly extending shoulder adjacent the lower end of said atomizer body, and spring means yieldably urging said plug into engagement with said shoulder to seal the lower end of said atomizer, said plug and intake tube being movable upwardly in said atomizer body against the bias of said spring to clean said discharge orifice.

13. In a flame photometer, a burner for producing an analytical flame comprising, means defining an expansion chamber having an open upper end, means for feeding an annular stream of combustible gas into said chamber, baffle means for diffusing said stream and for reducing the velocity thereof suflicient to produce a substantially quiescent mass of gas in said expansion chamber having a negligible velocity in the direction towards the open end of the chamber, means for directing a stream of combustion supporting gas through the chamber towards the open end thereof to draw combustible gas from the chamber and feed the combustible gas with the stream of combustion supporting gas to the flame, and an atomizer including a capillary tube having the upper end thereof disposed in said stream of combustion supporting gas and arranged to have liquid drawn therethrough by said stream of combustion supporting gas to inject a sample into the flame.

14. In a flame photometer, a burner for producing an analytical flame comprising, means defining an expansion chamber having an open upper end, means for feeding an annular stream of combustible gas into said chamber, bafile means for diffusing said stream and for reducing the velocity thereof in the direction towards the open end of the chamber, means for directing a stream of combustion supporting gas through the chamber'towards the open end thereof to draw combustible gas from the chamber and feed the combustible gas with the stream of combus tion supporting gas to the flame, an atomizer including a capillary tube having the upper end thereof disposed in said stream of combustion supporting gas and arranged to have liquid drawn therethrough by said stream of combustion supporting gas to inject a sample into the flame, said capillary tube extending downwardly below the burner, a casing surrounding the burner in spaced relation thereto and extending above the upper end of said expansion chamber to define a quiescent zone around the burner, said casing having an access door therein, means on said door for supporting a sample container for movement with the door to a position below the capillary tube as the dorr is moved to its closed position, latch means operable to latch the door in its closed position, and means responsive to movement of the latch means into and out of latching position for respectively elevating the sample container into operative position where the capillary tube dips into the sample in the container and for lowering the sample container below the lower end of the capillary tube.

15. In a flame photometer, a burner for producing an analytical flame comprising inner'wall means defining an inner chamber having a restricted orifice at the upper end thereof, an outer wall means extending around said inner wall means and defining an outer chamber around said inner wall means, said outer wall means extending above said inner wall means and having an open top, means communicating with said outer chamber below the upper end of said inner wall means for feeding a mixture thereto of a combustible gas and a combustion supporting gas, baffle means in said chamber below the upper end of said inner wall means for diffusing the gas mixture around said outer chamber and for reducing the velocity thereof in the direction toward the open end of the outer chamber, a screen on said outer wall means extending into closely spaced adjacency to said inner wall means and having an opening therein aligned with the orifice in said inner wall means for separating said outer chamber into a mixing and diffusing compartment below said screen and a combastion compartment above said screen, means for supplying a combustion supporting gas to said inner chamber to issue from said restricted orifice in a stream at a high velocity to entrain the combustible gas mixture which fl ws through said screen into the compartment thereabove and produce a flame sustaining mixture in the path of said stream, and means for introducing a sample to be analyzed into the interior of said stream of combustion supporting gas.

16. The combination of claim 15 wherein said baflle me"ns includes a first plate extending between said inner wall means and said outer wall means and having a plurality of annularly spaced openings therein, and a second plate mounted on said inner wall means and extending outw rdly therefrom in overlying relation to said openings in said first plate to deflect the gas issuing therefrom toward said outer wall means and reduce the velocity of said gas in a direction toward the open end of outer chamber.

17. In a flame photometer, a burner for producing an analytical flame comprising inner wall means defining an inner chamber having a restricted orifice at the upper end thereof, an outer wall means extending around said inner wall means and defining an outer chamber around inner wall means, said outer Wall means extending above said inner wall means and having an open top, means communicating with said outer chamber below the upper end of said inner wall means for feeding a mixture thereto of a combustible gas and a combustion supporting gas, baflie means in said chamber below the upper end of said inner wall means for diffusing the gas mixture around said outer chamber and for reducing the velocity thereof in the direction toward the open end of the outer chamber, a frusto-conical screen attached to said outer wall means adjacent said open top thereof and extending downwardly and inwardly into closely spaced adjacency to said inner wall means and having an opening therein aligned with said orifice in said inner wall means, said screen separating said outer chamber into a mixing and diflusing compartment therebelow and a combustion compartment above said screen, means for supplying a combustion supporting gas to said inner chamber to issue from said restricted orifice in a stream at a high velocity to entrain the combustible gas mixture which flows through said screen into the compartment thereabove and produce a flame sustaining mixture in the path of said stream, and means for introducing a sample to be analyzed into the interior of said stream of combustion supporting gas.

18. In an apparatus for flame photometry, a burner comprising a burner body having a connection for receiving a combustible gas, an atomizer body extending through said burner body and having a connection for receiving a combustion supporting gas, said atomizer body including a top wall having a discharge orifice therein for passing a stream of combustion supporting gas at a high velocity, a liquid intake tube extending through said atomizer body and through said orifice in the top wall thereof, said intake tube having an external diameter equal to the diameter of said orifice, a plurality of annularly spaced flow passages formed in the external periphery of said tube and spaced from the discharge end thereof to permit the flow of combustion supporting gas therethrough, and a reduced diameter cylindrical end on said intake tube extending from the discharge end thereof a distance less than the thickness of said top wall, said reduced diameter end having the outer surface thereof disposed radially outwardly from the radially inner edges of said flow passages to provide a restricted flow passage between said reduced end and the wall of said orifice whereby to form the stream issuing therefrom into a continuous annular sheath.

19. The combination of claim 18 including a plug secured to said tube intermediate the ends thereof, an inwardly extending shoulder on said atomizer body, and means yieldably urging said plug downwardly into engagement with said shoulder to seal the interface therebetween, said plug and intake tube being movable upwardly in said atomizer body to clean said discharge orifice.

20. The method of producing an analytical fl"me comprising, mixing a combustible gas and a combustion supporting gas in proportions to produce a mixture having insufficient combustion supporting gas to sustain a flame, maintaining a substantially quiescent mass of the gas mixture in a chamber having an open side in free communication With the atmosphere, introducing a jet of combustion supporting gas into the chamber at a point spaced inwardly from the open side to pass through the chamber toward the open side thereof and draw quantity of combustible gas mixture from the chamber whereby to produce a flame sustaining stream of combustible gas and combustion supporting gas, injecting a sample to be analyzed into the jet of combustion supporting gas to be carried therewith, and maintaining the velocity of the jet of combustion supporting gas at the point of introduction of the jet into the chamber above the velocity of flame propagation in the combined stream of combustible gas and combustion supporting gas whereby the combined stream burns at a point spaced from the point of introduction of the jet into the chamber to ionize the sample.

21. The method of producing an analytical flame comprising, mixing a combustible gas and a combustion supporting gas in proportions to produce a mixture having insufficient combustion supporting gas to sustain a flame, flowing the mixture into a chamber having an open side in free communication with the atmosphere at a rate suflicient to maintain a quantity of the gas mixture in the chamber, baflling the gas mixture in the chamber to reduce the velocity of the gas mixture in the direction 15 toward the open side of the chamber to substantially zero, introducing a jet of combustion supporting gas into the chamber at a point spaced inwardly of the open side to pass through the chamber toward the open side thereof and draw combustible gas mixture from the chamber whereby to produce a flame sustaining stream of combustible gas and combustion supporting gas, injecting a sample to be analyzed into the interior of the jet of combustion supporting gas to be carried therewith, and maintaining the velocity of the jet of combustion supporting gas, at the point of introduction of the jet into the chamber, higher than the velocity of flame propagation in the combined stream of combustible gas and combustion supporting gas whereby the combined stream burns at a point spaced from'the point introduction of the jet into the chamber to ionize the sample.

22. In a flame photometer, a burner for producing an analytical flame comprising an upright burner body having a connection for receiving a supply of combustible gas, an injector disposed concentrically to said body and having a connection for receiving a combustion supporting gas, said injector having an orifice in the upper end thereof for discharging a' jet of combustion supporting gas, a housing surrounding said burner body and extending upwardly from the upper end of the injector, said burner body having passages therein disposed below the upper end of said injector for producing an upwardly flowing annular stream of combustible gas surrounding the injector, bafile means overlying said passages and disposed below the upper end of said injector and in the path of flow of said combustible gas stream for reducing the velocity thereof sufficient to produce a substantially quiescent mass of gas having a negligible velocity in the direction of flow of said jet of combustion supporting gas, and means for introducing a sample to be analyzed into said jet of combustion supporting gas to be carried thereby to the flame.

References Cited in the file of this patent UNITED STATES PATENTS 424,024 Rawlings et al Mar. 25, 1890 1,204,359 Kemp et a1 Nov. 7, 1916 1,596,609 Gault Aug. 17, 1926 1,729,677 Miller Oct. 1, 1929 1,741,532 Morse Dec. 31, 1929 1,800,616 Forster Apr. 14, 1931 2,532,687 Weichselbaum Dec. 5, 1950 2,562,874 Weichselbaum July 21, 1951 2,664,779 White Jan. 5, 1954 2,714,833 Gilbert Aug. 9, 1955 2,769,366 Honma Nov. 6, 1956 :UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,015,383 January 9 1962 John J, J. Staunton It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 12, lines 22 to 241 strike out "sufficient to produce a substantially quiescent mass of gas having a negligible velocity in the direction toward the open end of the chamber" and insert the same after ('zhanrlher in line 26 same column 12 Signed and sealed. this 1st day of May 1962.

(SEAL) Attest:

' DAVID L. LADD ERNEST W. SWIDER Attesting Officer (lommlssloner of Patents 

